https://dba.stackexchange.com/questions/56/how-to-determine-if-an-index-is-required-or-necessary
http://blog.celerity.com/how-to-design-sql-indexes
http://blog.celerity.com/how-to-design-sql-indexes
22/08/2017, 19:03:36B-Trees in databases are not binary trees, they are BALANCED trees
MIPA